Once, when high on LSD, recounts the author and neurologist Oliver Sacks in his new book, Hallucinations, he was obsessed with the colour indigo. “It was the colour of heaven,” he writes. Sacks was desperate to see it—so much so that he began to conjure up a blob of indigo in his mind.

The lactarius indigo could have saved him a trip. The mushroom’s whitish cap looks deceptively plain, but if you flip it over, the gills are a brilliant blue. Slice into it, and the mushroom bleeds indigo-coloured milk. Cook it, and the flesh turns a greyish green. “It’s a green you’ve never seen in cooking,” says Fidel Brochu, a Quebec-based wild mushroom distributor who picked the lactarius indigo in Saskatchewan’s Torch River Provincial Forest last summer. When chef Gilles Herzog at F Bar in Montreal served them as a garnish, simmered in olive oil and cider vinegar, he made sure to explain what they were to his diners. “Sometimes clients find them bizarre,” he says. The mushrooms can be as small as a toonie or as large as dinner plates. Take a bite, and “it’s extraordinary,” says Elisabeth Poscher, who also harvests the mushroom. “It has a peppery taste. It’s—I don’t know. You have to try it.”

Up until recently, though, you had to be lucky to do so in Canada. While you can buy lactarius indigo at village markets in Guatemala, says Poscher, and in Europe there’s a trade in a related mushroom variety commonly known as the saffron milk cap (it bleeds yellow), it had never been commercialized here until recently. “It’s a rare mushroom. It’s pretty hard to find an area that can justify commercial picking,” says Brochu.

But in the Torch River forest, indigo mushrooms thrive every year. “They get huge,” says Lorne Terry, a mushroom buyer in nearby White Fox, around 400 km north of Regina. The forest, which is on Crown land, already produces what are considered to be some of the best chanterelles in the world, and pickers come from nearby White Fox and reserves in the area to get in on that market.

When the lactarius indigo was shipped out and sold in Quebec and Ontario last summer, consumers and chefs wanted more. Jonathan Forbes, owner of a wild foods supply company, sold them easily to the public at Toronto farmers’ markets for $22 a pound. Another mushroom broker, Pascal L’Archeveque, supplied chefs in Montreal who were interested in experimenting with the indigo.

But buyers now believe this trade is under threat. The provincial government is putting together a forest management plan because it says the wood in the Torch River forest is old and in a perilous state, susceptible to wind storms, insects, disease or the forest fires that are part of the natural cycle of the local ecology. The answer: logging some of the old wood. “You can either be proactive or let Mother Nature take its course,” says Bruce Walter, a forester with the provincial Ministry of Environment. Which could be devastating, he adds, because a forest fire could burn down the whole forest in an afternoon.

A public consultation took place this month, but those involved in the mushroom business are worried. Mushrooms like the indigo sprout from underground mycelium that can disappear when soil is disturbed by the machinery used to fell trees, and chanterelles feed off the root systems of the old Jack pines in the forest. Dylan Gordon, a doctoral student at the University of Toronto, says the supply in the forest is irreplaceable. Terry, for one, has been trying to stop the logging. He estimates at least a third of the town participates in the mushroom industry. “Don’t get me wrong, I’m not a tree hugger,” he says. But if the forest is logged, “You can basically kiss it goodbye.”

According to Guy Langlais, a researcher with the Quebec organization Biopterre, one hectare of wild mushrooms is worth $400 to $500 a season. The Torch River forest stretches 4,000 hectares. And the commercial value of the indigo has yet to be seen. It can be sold fresh or dried, and interest is just beginning.

“All mushrooms are great, but this one is amazing,” says Poscher, searching for the fitting superlative. “It is outstanding. Extraordinary.”